Difference Between Accelerometer and Gyroscope

Posted on November 11, 2012 by admin Last updated on: November 11, 2012

Accelerometer vs Gyroscope

The Accelerometer and gyroscope are two motion sensing devices commonly used in modern technological equipment. Their operation is based on the concept of inertia, which is the reluctance by masses to change its state of motion, hence called inertial measurement units in engineering applications.

Accelerometer, as the name implies, is used to measure the linear acceleration, and gyroscopes are used to measure various rotational movement parameters. Combining the information obtained from the two devices, the motion of an object in the 3-d space can be calculated and projected to a high degree of accuracy.

More about Accelerometer

The accelerometer is a device used to measure the proper acceleration; i.e. the physical acceleration experienced by an object. It does not necessarily measure the rate of change of velocity in that frame, but the acceleration experienced by the body or frame. An accelerometer displays an acceleration of 9.83ms-2 on earth, zero in free fall and space, when at rest. Simply put, the accelerometer measures the g-force acceleration of the object or the frame.

In general, the structure of an accelerometer has a mass connected to a spring (or two). The elongation of the spring under the force exerting on the mass gives a measure of the acceleration proper acting on the system or the frame. The magnitude of the elongation is converted into an electrical signal by a piezoelectric mechanism.

Accelerometers measure the g-force acting on the body and measure only linear acceleration. It cannot provide accurate measurements about the rotational motion of the body, but can provide information about the angular orientation of the platform by the tilt of the gravity vector.

Accelerometers have applications in almost any field that require motion of a machine in 3-d space to be measured and in measurements of the gravity. The inertial navigation system, which is an essential part of the navigation system of the aircrafts and missiles use high precision accelerometers and the modern mobile devices such as smart phones and laptops also use them. In heavy machinery, accelerometers are used to monitor the vibration. Accelerometers have a significant presence in engineering, medicine, transport systems, and consumer electronics.

More about Gyroscope

A gyroscope is a device for measuring orientation of a platform and operates based on the principle of conservation of angular momentum. The principle of conservation of angular momentum states, when a rotating body attempts to change its axis, the body displays reluctance to the change, to conserve its angular momentum.

In general, mechanical gyroscopes have a rotating mass (usually a disk) attached to a gimbal by a rod acting as the axis. The mass rotates incessantly, and when there is a change in the orientation of the platform, in any of the three dimensions, it remains for a while in its original position. From the measurement of the changes of position of the gyroscope frame relative to the axis of rotation, information about the change of angular orientation can be acquired.

Combining this information with accelerometers, an accurate image of the position of the frame (or object) in 3-d space can be created.

Like accelerometers, the gyroscopes are also a main component of navigation systems and any engineering field that relates to motion monitoring. In modern consumer electronic devices, especially mobile devices such as smart phones and handheld computers, both accelerometers and gyroscopes are used to maintain the orientation, to keep the display always in the right direction. However, these accelerometers and gyroscopes are different in structure.

What is the difference between Accelerometer and Gyroscope?

• The accelerometer measures proper linear acceleration such as g-force.

• While, gyroscopes measure the change in orientation using the variation of the angular properties such as angular displacement and angular velocity.